Percussion hammer drill



June 20, 1967 G. s. JONES, JR

PERCUSSION HAMMER DRILL 2 Sheets-Sheet 1 Filed Dec. 23, 1964 INVENTOR GROVER S. JONES JR.

ATTORNEY June 20, 1967 G. s. JONES, JR

PERCUSSION HAMMER DRILL Filed Dec. 23,1964

2 Sheets-Sheet 2 m. QE

INVENIOR GROVER S. JONES JR.

ATTORNEY United States Patent This invention relates to drilling devices and it is more particularly concerned with drills which function by impact or percussion forces.

Conventional impact or percussion drills comprise generally a solid bar of substantial weight, Le, a thousand or more pounds, vertically suspended at the end of a rope or cable. The other end of the cable is connected to a winch, and means are provided between the winch and the bar to raise the bar and allow it to drop repeatedly at a given rate in a selected location where the drilling is to be performed. The bar has a bit or cutting tool at its bottom end. When the drill is repeatedly dropped, the impacts of said bit with the surface to be broken accomplish the useful work. Powered machinery acting through the winch repeatedly re-energizes the drill by lifting it to a proper height for dropping.

The mechanical efliciency of such conventional drilling devices is markedly poor. The energy input is very high compared to the energy actually expended to do useful work. Furthermore, only a very small percentage of the capacity potentially available through the powered winch is converted to useful work. On each dropping of the bar the potential energy achieved in raising it is spent between the useful work performed by the bit, damping and impact losses that accomplish no useful work, and the energy of rebound which serves only to lower the energy input requirement of the powered machinery in relifting the drill to a proper dropping height.

The general object of the present invention is the provision of an impact on percussion hammer drill having increased efficiency in comparison with conventional drills.

A specific object is the provision of means in combination with a conventional drilling rig which is effective to increase the mechanical efiiciency of the system as a whole.

Another object of the invention is the provision of means in combination with a conventional drilling rig for fuller utilization of the potential work capacity available through the powered machinery to increase drilling efficiency.

Still another object of the invention is the provision of a drill of the type mentioned having means for absorbing energy lost in conventional percussion drills and utilizing the absorbed energy to perform useful work.

A still further object is the provision of a drill of the type mentioned which is rugged, easy to manufacture, and simple to use.

A still further object is the provision of a method of operating a percussion drill to achieve increased efliciency.

A still further object is the provision of improvements in percussion hammer drills of the type described in my co-pending application Ser. No. 397,539, filed on Sept. 18, 1964.

These and still further objects, advantages and features of the invention will be apparent from the description which follows in conjunction with the accompanying drawing to which the description refers.

In the drawing:

FIG. 1' is a side elevational view of a conventional drilling rig, partly broken away, in combination with a percussion hammer drill comprising an embodiment of the invention.

FIG. 2 is a longitudinal sectional View of the embodiment, partly broken away.

3,326,303 Patented June 20, 1967 FIGS. 3-17 comprise a series of schematic diagrams illustrating sequentially the action of the embodiment.

Referring to the drawing with more particularly, there is diagrammatically illustrated in FIG. 1 a conventional drilling rig 21 mounted on an ordinary truck 22. The rig 21 comprises a powered winch 23 about which one end of a cable 24 is wound. The cable passes from the winch 23 over a stationary sheave 25, then under a sheave 26 mounted at the end of an oscillating beam 27, and, thence, to the top of a derrick 28 where it passes over a sheave 29 and then vertically downward to the drill device 30. The drill device 30 conventionally operates in casing sections 31, these sections being connected together serially and lowered into the ground as the drilling progresses.

The embodiment comprises a header 32 to which one end of the cable 24 is directly or indirectly attached in any conventional manner. The bottom of the header 32 has a recessed portion 33 to which the upper end of a tubular shell 34 is secured such as by shrink fitting or by any other suitable means. An anvil 35 in the form of a solid plug has an upper annular recessed portion 36 to which the lower end of the shell 34 is secured such as by shrink fitting or any other suitable means. The bottom of the anvil 35 also has an annular recessed portion 37 to which the upper end of another tubular shell 38 is secured by the same or similar means.

A socket 39 has an upper end wall 40 and a cylindrical hollow portion 41 between the wall 40 and its lower end. The wall 40 has a recessed portion 43 which engages and is secured to the bottom of the shell 33.

The bit 44 of the drill has a cylindrical portion 45 which is disposed in and which reciprocates in the hollow portion 41. From the upper end of the cylindrical portion 45 a rod-like stem 46 projects upwardly through a central opening 47 in the wall 40. The upper end of the stem 46 is secured in an opening 48 at the bottom of a head 49. The head 49 reciprocates in the space 50 of the tubular shell 38 between the bottom of the anvil 35 and the top of the end wall 40 as the stem 46 reciprocates with the bit 44, including the cylindrical portion 45, as a unit.

The :bit 44 is biased to its downward position by means of a coil spring 61 about the stem 46 and between the bottom of the wall 40 and a pressure ring 52 on an upwardly facing shoulder 53 of the cylindrical portion 45.

A hammer 54 in the form of a cylindrical solid bar is disposed for vertical reciprocation within the shell 34 be tween the header 32 and the anvil 35. A coil spring 55 is seated against an upwardly facing shoulder 56 of the anvil 35 about an upwardly extending nipple 57.

The upper end of the spring 55 is set against the bottom of the hammer 54 and thereby functions to urge it upwardly against the header 32.

When the device is elevated by the winch cable 24 and then dropped, the bit 44 strikes the work surfaces 58 as the cycle begins. See FIG. 3. Upon striking the work surface, the bit rebounds against the force of the spring 51 as the device, as a unit, continues to fall. When the downward movement of the device is arrested, momentum of the hammer 54 carries it downward against the force of the spring 55 until it strikes the anvil 35 on top of the member 57. In the meantime, the bit 44 in its upward movement results in its hammer head 49 striking the bottom of the anvil. It is rebounded under this impact and under the energy stored in the compressed spring 51. There is also added to this force, rebound energy delivered by the hammer 54 acting through the spring 55 and the anvil 35. The actionis diagrammatically illustrated in sequence in FIGS. 3-17. For simplicity, only seven impacts are illustrated, but in actual practice may exceed seven impacts per cycle, a cycle consisting of a raising and lowering of the tool as a whole by the rig 21. The specific reciprocating action of the bit 44 in actual operation is quite rapid, likea vibration, while the action of the hammer 54 is more in synchronization with the action of the anvil 35, the latter being directly controlled by the rig 21, because of its direct connection to the header 32, through the tubular shell 34.

This action can be controlled through controlled op eration of the rig winch to achieve the operating conditions desired in any particular case.

The weight of the members can be varied to provide different operating characteristics but for optimum efficiency the weight of the hammer and the weight of the anvil 35, and parts attached directly thereto, namely, the tubular shells 34 and 38, should be substantially equal to each other, and about three times or more the weight of the drill bit and parts connected thereto.

In a conventional solid bar drill of weight W which is dropped in such a manner as to strike the ground with a velocity magnitude M the energy E, immediately preceding imp-act with the bottom of the bore is given by the formula:

1 W E: (a)

The ratio of the velocity with which the drill bounces from the bottom of the bore divided by Li may be termed the coefficient of restitution k and k will always be less than unity. In the range of weights to be considered it may be assumed to be independent of W. Thus, the magnitude of the rebound velocity in ku and the energy in the drill immediately following impact with the bottom of the bore is given by the formula:

Therefore, the energy delivered to the ground (the energy with which drilling must be accomplished) is given by the formula:

The harder the surface presented by the bottom of the bore the closer the value of k will be to unity. Then, for very hard surfaces only a small fraction of the total energy E in the drill in each cycle immediately preceding impact is utilized to do useful work. The majority of the energy, neglecting losses due to damping and impacts with the sides of the bore, remains in the drill and is functional only in reducing the work load on the powered winch in relifting the drill to the dropping position for the next cycle.

Assuming that the overall weight of drill embodying the teaching of the instant invention has the same weight W as a conventional solid bar drill and that R denotes the weight of the hammer assembly divided by the weight of the bit assembly, and that R denotes the weight of the casing assembly divided by the weight of the bit assembly. The weight of the spring is small enough by comparison to be neglected. In a typical drilling operation, optimal results are realized with R and. R exceeding three. Let a as previously defined by the velocity of the anvil assembly immediately preceding its first impact with the bottom of the bore in a given cycle. Let a 14;; u denote its velocity immediately preceding its second, third n impact with the bottom of the bore respectively. If m denotes the mass of the bit assembly, the energy E delivered to the ground by a Weight equivalent conventional solid bar drill in one hoisting-dropping cycle is given by the formula:

In the drilling action as depicted in FIGS. 3 to 17, the total energy E delivered is given by the formula:

n= 1 2 3 4 5 s 7 where u a a 11,, u u H7 are the velocities of impact 4 as depicted in FIGS. 3, 5, 7, 10, 12, 14, and 16, respectively. If, in general, there are n impacts with the bottom of the bore then the energy delivered is given by the formula:

Assuming that the collisions between the anvil 35 and the bit head 49 is perfectly elastic and that the same is true for collisions between the hammer 52 and the anvil 35, the successive velocity magnitudes are readily computed. In general, in this three member system, subsequent velocities can exceed u several times over. This is made possible by the favorable momentum transfer resulting from the fact that the anvil and the hammer are several times heavier than the parts movable with the bit.

Carrying out the indicated calculations with k chosen so as to reflect rebound velocities for reasonably hard rock, for drill designs incorporating appropriately chosen weight ratios between components and properly chosen spring compressions, the ratio E /E will exceed three. Thus, a greatly increased drilling efficiency is possible with the present invention as compared to conventional equipment or previously devised similar equipment.

Let G be the length of the gap between the head 49 and the anvil 35. Let G be the length of the gap between the anvil and the hammer 52. For proper functioning an appropriate ratio between G and G exists at the moment of first impact as depicted in FIG. 3. Several synchronizations are possible, but in general best results are obtained for:

In particular, G =1 inch and G =3 inches has been found to be a good choice. G /2 inch and G =l /2 inches also works well.

Since more energy is expended by using the present invention, it is clear that more energy must be put into the system. This is accomplished by using a heavier work load on the powered winch in hoisting the drill to dropping height for the next cycle. This work load is made heavier by virtue of the fact that there is less rebound energy available than with conventional equipment.

I claim:

1. A percussion hammer drill comprising an anvil, a first tubular body secured to the anvil and projecting upwardly therefrom, a second tubular body secured to the anvil and projecting downwardly therefrom, a hoisting cable header secured to the top of the first tubular body, a drill bit below the anvil mounted for vertical reciprocation on the second tubular body, said drill bit having a hammer head within the second tubular body, a hammer bar disposed in the first tubular body for reciprocation between the anvil and header, resiliently yieldable means urging the hammer bar upwardly relative to the anvil, resiliently yieldable means urging the drill bit and hammer head, as a unit, downwardly relative to the anvil.

2. A percussion hammer drill comprising an anvil, a first tubular body secured to the anvil and projecting up wardly therefrom, a second tubular body secured to the anvil and projecting downwardly therefrom, a hoisting cable header secured to the top of the first tubular body, a drill bit below the anvil mounted for vertical reciprocation on the second tubular body, said drill bit having a hammer head within the second tubular body, a hammer bar disposed in the first tubular body for reciprocation between the anvil and header, resiliently yieldable means urging the hammer bar upwardly relative to the anvil, resiliently yieldable means urging the drill bit and hammer head, as a unit, downwardly relative to the anvil and means limiting the lowermost section of the hammer head in relation to the anvil under the action of the resiliently yieldable means.

1301' most opera-tions optimal results are obtained with G1 in the range from inch to 1 inch.

3. A percussion hammer drill as defined by claim 2 in which the weight of the anvil and parts connected thereto is substantially three times the weight of the drill bit.

4. A percussion hammer drill as defined by claim 2 in which the weight of the anvil and parts connected thereto is substantially three times the weight of the hammer bar.

5. A percussion hammer drill as defined by claim 2 in which the weight of the anvil and parts connected thereto is substantially three times the weight of the drill bit and parts connected thereto and substantially equal to the weight of the hammer bar.

6. A percussion hammer drill as defined by claim 2 in which the distance between the anvil and the hammer bar, when the hammer bar is in its uppermost position is about 2-4 times the distance the anvil and its hammer head, when the latter is in its lowermost position.

7. A percussion hammer drill as defined by claim 2 in which the distance between the anvil and the hammer bar,

when the hammer bar is in its uppermost position is about three times the distance between the anvil and the hammer head, when the latter is in its lowermost position.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 8/1960 Canada. 12/1933 France.

FRED C. MATTERN, 1a., Primary Examiner.

L. P. KESSLER, Assistant Examiner. 

1. A PRECUSSION HAMMER DRILL COMPRISING AN ANVIL, A FIRST TUBULAR BODY SECURED TO THE ANVIL AND PROJECTING UPWARDLY THEREFROM, A SECOND TUBULAR BODY SECURED TO THE ANVIL AND PROJECTING DOWNWARDLY THEREFROM, A HOISTING CABLE HEADER SECURED TO THE TOP OF THE FIRST TUBULAR BODY, A DRILL BIT BELOW THE ANVIL MOUNTED FOR VERTICAL RECIPROCATION ON THE SECOND TUBULAR BODY, SAID DRILL BIT HAVING A HAMMER HEAD WITHIN THE SECOND TUBULAR BODY, A HAMMER BAR DISPOSED IN THE FIRST TUBULAR BODY FOR RECIPROCATION BETWEEN THE ANVIL AND HEADER, RESILIENTLY YIELDABLE MEANS URGING THE HAMMER BAR UPWARDLY RELATIVE TO THE ANVIL, RE- 